A. Field of the Invention
This invention is in the field of dental prostheses and methods and apparatus for manufacturing dental prostheses and for installing dental prostheses in a patient's mouth.
B. Prior Art Patents and Publication
“NobelGuide—Procedures & Products Powered by Procera®” ©Nobel Biocare Services AG 2005,
U.S. Pat. Nos. 5,595,703; 5,768,134; 6,361,318; 6,821,123; 6,848,909; and 6,902,401.
C. Prior Art Procedures and Apparatus
1. In describing prior art procedures and apparatus the following terminology and definitions are commonly used.
Dental Prosthesis means an artificial tooth or a series of artificial teeth that is used to cosmetically and functionally restore missing or damaged teeth in a patient.
Implant means a structure that is implanted in a patient's bone as an anchor for a dental prosthesis. The typical dental implant is an externally threaded cylinder that is placed into a hole that is drilled into a patient's bone. The top of the implant has a collar part to receive an abutment.
Abutment means a structure that is attached to an implant to create a mounting feature for a prosthesis.
Angled abutment means a type of abutment that allows a prosthesis to be fixed to a patient's mouth, along an axis that differs from the axis of the implant.
Model means a casting of a patient's mouth that is used to select or construct abutments, and prosthesis.
Transfer post means a device that is inserted into an implant that has been placed in a patient's mouth. It is used to record the position of implants to facilitate the construction of a model.
Analog means a device that is used to simulate a dental implant in a cast model of a patient's teeth.
Surgical guide means a fixture that is used by a surgeon to aid in the positioning of drilled holes for placing implants. It can also be used to position analogs during the construction of a model.
Analog Mount means a device that is used to temporarily position an analog in a surgical guide during the model casting process.
Implant Driver means a tool that is used to screw implants into a patient's bone
Fixture Mount means a device that is inserted into the implant and used to accurately pilot an implant through the surgical guide during surgery. It is rotated by an implant driver.
Tissue side and mouth side of the surgical guide: tissue side means the side of the guide to be positioned directly adjacent the tissue of the mouth; mouth side means the side opposite the tissue side, mouth side being the exposed side when the surgical guide is positioned in the mouth for drilling and implant attachment through guide holes in the guide.
2. Traditional Manual Technique to Make and Install Dental Prostheses One basic prior art technique for creating and attaching dental prostheses is described herein and illustrated in Story Board A attached hereto as Appendix A. With this procedure an implant is secured in the jaw bone where a tooth is missing or is to be replaced, an abutment is secured to the implant and the final prostheses is secured to the abutment. Implants are typically installed so that the top of the implant or collar of the implant is flush with the bone and below the gum tissue. The collar of the implant has internal threads that receive a screw to hold an abutment or prosthesis. The collar also has an internal or external coupling or an axial keying feature such as a triangular, hexagonal or octagonal in cross-section that allows a driver to securely engage the implant to be screwed into the bone. This feature can also be used to lock the rotational position of an abutment or prosthesis secured to the implant.
Angled abutments can produce a more aesthetic result by allowing location of the prosthesis in the ideal position relative to other teeth, even if the supporting bone is not directly beneath the prosthesis. Angled abutments also allow the surgeon to use the strongest available part of the bone to support the implant even though it may not be directly beneath the prosthesis.
When replacing a single tooth it is critical that the prosthesis mounted in its initial rotational orientation, is secured from later rotating away from this orientation. This is not an issue when multiple adjacent teeth are replaced, because the replacement teeth are joined together in a single prosthesis and thus cannot rotate relative to each other. To properly orient a prosthesis, a recording of data defining the rotational position of the implant is necessary to be used for construction of an angled abutment, because angled abutments and prostheses are constructed and fitted to a model before they are placed in a patient. The prosthesis will align properly in the patient's mouth only if the analog, when the prosthesis is made, has the same position and has the same rotational alignment in the model as the final implant has in the patient's mouth.
The prior art procedure includes taking an impression (casting) of the patient's mouth, after the implant has been placed. During the impression process the position of the implant is recorded, and then a transfer post is attached to the implant with a coupling that bars relative rotation of the transfer post relative to the implant. Thereafter, casting material is applied. When the casting material has set the impression with the imbedded transfer post is removed from the patient's mouth and is then typically sent to a dental lab. At the lab an analog is attached to the transfer post, and casting material is poured into the impression and around the analog. When the material is set, the impression and transfer posts are removed from the casting, leaving a model of the patient's mouth with the analog in the same position (including rotational) as the implant is in the patient's mouth. The abutment and prosthesis are then constructed and fitted to the model. When complete, the prosthesis is returned to the dentist and installed in the patient's mouth.
This traditional technique is illustrated schematically and pictorially in FIGS. A1-A12 in the above-noted Story Board A of Appendix A, which shows a succession of stages or steps described below. The illustrations of these steps are preceded by FIG. A which shows as the conclusion of these steps, a prosthetic crown attached to an abutment attached to an implant in a patient's jaw bone.
FIG. A1 illustrates a patient's jaw with a missing tooth.
FIG. A2 indicates drilling a hole in the bone to receive an implant. FIGS. A3 and A4 show placement of the implant.
FIG. A5 shows installing a transfer post into the top of the implant, the top of the transfer post extending upward to the vicinity of the top level of the adjacent teeth.
FIG. A6 shows that an impression is made of the area of the implant and the adjacent teeth on either side of the area of the implant. The impression includes recesses representing the adjacent teeth, the area of the implant and attached to the impression is the transfer post.
FIGS. A7 and A8 show that the impression, with the transfer post included, is removed from the mouth and sent to a dental laboratory. Here, an analog is attached to the exposed top of the transfer post exposed above the surface of the impression, the analog simulating the implant.
FIG. A9 shows that said impression, which includes the exposed top of the transfer post and the analog attached to said transfer post, is cast, thus creating a “model” of the patient's relevant mouth structure with the attached analog. The impression includes a series of recesses which represent negative spaces corresponding to the positive shapes of existing teeth.
FIG. A10 shows that a model is cast from the impression. The result is a model of the patient's teeth including the space of the missing tooth and the attached analog. Now the model is used by a lab technician to build an appropriate abutment and prosthesis.
FIGS. A11 and A12 show that later this abutment and final prostheses are attached to the patient's mouth.
The final prosthesis may cooperate with (a) a straight line abutment whose axis is generally aligned and coaxial with the implant, or (b) an angled abutment which allows a prosthesis to be fixed in a patient's mouth along an axis which differs from the axis of the implant.
3. Prior art computer aided Rapid Replacement Method—If a patient does not require angled abutments and does not have a single tooth replacement that needs to be rotationally secured, the process can be done more rapidly with the computer aided procedure commonly known as the “Rapid Replacement Method”. Here, a surgical guide can be used to construct a model and prosthesis prior to the surgery for installing the implants. The dentist then uses the same surgical guide to perform the implant placement surgery. After the surgery, but in the same visit, the abutments and implants are attached, and a patient can leave the dentist's office with a temporary or final prosthesis. Thus, the patient can have all the surgery and implants in a single visit.
The above-noted computer aided Rapid Replacement Method includes a succession of stages and/or steps, as follows.
An impression is taken of the patient's upper and lower mouth, typically with a tray positioned adjacent the teeth and gums. From the impression a denture is made, to which is added radio opaque markings that will be highly visible in a CT scan and will identify specific locations to facilitate computer aided surgical planning for drilling locations.
A CT scan is taken of the patient's mouth and of the radio opaque denture, to show the underlying jaw bone structure and existing teeth and problem area.
With computer software and input from the surgeon a surgical guide is designed and created which indicates optimum choices of bone and optimum locations and angular alignments for drilling and placement of implants. The surgical guide made directly from the computer developed data, includes a tissue side corresponding generally to the shape and contour of the patient's upper or lower mouth, and an opposite mouth side, peripheral edges and drill guide holes in the optimum locations relative to the existing jaw bone structure and at predetermined locations relative to said peripheral edges and having predetermined angular alignment relative to said tissue side surface. Drill guide sleeves are situated concentrically in said drill guide holes.
Various abutments are fitted to the model that correspond to each of the implants which are intended to be installed after drilling. Then a temporary or final prosthesis is made to fit the abutments of the model, this prosthesis to be later attached permanently in the patient's mouth.
The surgical guide is then secured (temporarily) to the patient's mouth, and holes for the implants are drilled through the guide sleeves of the surgical guide. Next, the implants are inserted through the guide sleeves of the surgical guide and into the holes drilled in the bone for the implants, and the implants are screwed into place, and the drill guide is removed. The abutments are attached to the implant and a temporary or final prosthesis is attached to the abutments.
A deficiency in this Rapid Replacement method is that it is not suitable for patients who require angled abutments or for patients who need single tooth replacements that require rotational stability via the implant. The reason for this is that the current surgical guides do not indicate the intended rotational position of the implant. Without this indication the rotational alignment of the analog used in the construction of the model and the abutment and prosthesis cannot accurately or reliably correlate to the rotational alignment of the implants that are placed in the patient's mouth.
When used for the Rapid Replacement Method, the existing surgical guides are only suitable for screw retained prostheses where multiple straight abutments are used. Computer generated guides can still be used for angled abutments or single tooth replacement, but the abutments and prosthesis cannot be created prior to the surgery to install the implants.